Bumjun Kim

Bumjun Kim

Ph.D. Student in Artificial Intelligence
Yonsei University
Artificial Intelligence & Information Systems Laboratory (AI-ISL)
Advisor: Prof. Albert No

I am a Ph.D. student in Artificial Intelligence at Yonsei University, advised by Prof. Albert No in the Artificial Intelligence & Information Systems Laboratory.

My research focuses on understanding the mechanisms that shape the capabilities and limitations of diffusion language models and using these insights to develop more reliable and efficient generation methods.

peer-reviewed publications

(*) denotes equal contribution, (†) denotes corresponding author.

  1. ICML
    DAPD: Dependency-Aware Parallel Decoding via Attention for Diffusion LLMs
    Bumjun Kim*, Dongjae Jeon*, Moongyu Jeon*, and Albert No†
    In the International Conference on Machine Learning, 2026.

    Parallel decoding for diffusion LLMs using attention-derived dependency structure.

  2. ICLR
    Rainbow Padding: Mitigating Early Termination in Instruction-Tuned Diffusion LLMs
    Bumjun Kim*, Dongjae Jeon*, Dueun Kim*, Wonje Jeung, and Albert No†
    In the International Conference on Learning Representations, 2026.

    A method for reducing early termination in instruction-tuned diffusion language models.

  3. CVPRFindings
    Memorization In Stable Diffusion Is Unexpectedly Driven by CLIP Embeddings
    Bumjun Kim and Albert No†
    In the IEEE/CVF Conference on Computer Vision and Pattern Recognition, 2026 Findings.

    An analysis of Stable Diffusion memorization that identifies CLIP embeddings as a key driver.

  4. NeurIPS
    A Theoretical Analysis of Why Masked Diffusion Models Mitigate the Reversal Curse
    Moongyu Jeon*, Sangwoo Shin*, Bumjun Kim, Kyelim Lee, and Albert No†
    In Advances in Neural Information Processing Systems, 2026.

    Identifies any-order masked supervision, full attention, and position-invariant value vectors as key mechanisms behind reversal-curse mitigation.

  5. EMNLP
    Same Trajectory, Contradictory Rewards (ROBORMBENCH): Paraphrase Fragility in Vision Language Reward Models
    Wonje Jeung, Sangyeon Yoon, Hyesoo Hong, Yoonjun Cho, Dongjae Jeon, Bumjun Kim, Jean Oh†, Youngjae Yu†, and Albert No†
    In the 2026 Conference on Empirical Methods in Natural Language Processing (Main Conference).

    A benchmark revealing the fragility of vision-language reward models to paraphrases of identical robot trajectories.

preprints

  1. arXiv
    Low-Confidence Remasking Traps Flexibility: Realizing Arbitrary-Order Potential for Diverse Rollouts in Diffusion LLMs
    Moongyu Jeon*, Dongjae Jeon*, Bumjun Kim, Mingyu Kim†, and Albert No†
    arXiv preprint, 2026.

    Shows that low-confidence remasking, rather than arbitrary-order generation, suppresses rollout diversity, and introduces entropy-guided initialization to improve exploration.

workshop papers

  1. ICML-W
    Single-Step Initialization for Exploratory Parallel Rollouts in Diffusion LLMs
    Dongjae Jeon*, Bumjun Kim*, Mingyu Kim†, and Albert No†
    In the ICML Workshop on Structured Probabilistic Inference & Generative Modeling, 2026.

    Improves exploration in dLLM RL post-training by unmasking one randomly selected position before decoding to diversify parallel rollouts.

education

Yonsei University
Ph.D. in Artificial Intelligence, Mar 2025 - Expected Feb 2030 · Seoul, Korea
GPA: 4.24/4.30
Hongik University
B.S. in Computer Engineering, Mar 2018 - Feb 2025 · Seoul, Korea
GPA: 3.89/4.50

research experience

Ph.D. Researcher, AI-ISL
Yonsei University, Mar 2025 - Present · Advisor: Prof. Albert No
Research on the mechanisms underlying diffusion language models and on reliable and efficient methods for parallel decoding, instruction tuning, and RL post-training.
Undergraduate Researcher, AI-ISL
Jul 2023 - Feb 2025 · Advisor: Prof. Albert No
Studied memorization in image diffusion models and built analysis pipelines for privacy experiments across Stable Diffusion variants.

honors & awards